Adhesive for high-frequency dielectric heating, structure, and method for manufacturing structure

Abstract

A high-frequency-dielectric-heating adhesive for bonding three or more adherends to each other is provided. A dielectric property DP1 of the adhesive and a dielectric property DP2 of each of the adherends satisfy a numerical formula (Numerical Formula 1). The adherends are each an adherend having no flow start temperature or an adherend having the flow start temperature. A flow start temperature TF2 (degrees C.) of the adherends and a flow start temperature TF1 (degrees C.) of the adhesive satisfy a numerical formula (Numerical Formula 2). The dielectric properties DP1, DP2 are defined by values of dielectric properties (tan δ/ε′r), where tan δ and ε′r are respectively a dielectric dissipation factor and a relative permittivity at 23 degrees C. and a frequency of 40.68 MHz,0<DP1−DP2  (Numerical Formula 1)−5≤TF2−TF1  (Numerical Formula 2).

1 . A high-frequency-dielectric-heating adhesive configured to bond three or more adherends to each other, the high-frequency-dielectric-heating adhesive comprising:
 a thermoplastic resin; and   a dielectric filler configured to generate heat upon application of a high-frequency electric field, wherein   a dielectric property DP1 of the high-frequency-dielectric-heating adhesive and a dielectric property DP2 of each of the adherends satisfy a relationship of a numerical formula (Numerical Formula 1) below, and   the three or more adherends each have a flow start temperature or no flow start temperature, a flow start temperature TF2 (degrees C.) of each of the adherends and a flow start temperature TF1 (degrees C.) of the high-frequency-dielectric-heating adhesive satisfy a relationship of a numerical formula (Numerical Formula 2) below,
   0<DP1−DP2  (Numerical Formula 1)
 
   −5≤TF2−TF1  (Numerical Formula 2)
 
   
       where the dielectric property DP1 and the dielectric property DP2 are respectively values of dielectric properties (tan δ/ε'r) of the high-frequency-dielectric-heating adhesive and the three or more adherends,
 tan δ is a dielectric dissipation factor at 23 degrees C. at a frequency of 40.68 MHz, and 
 ε'r is a relative permittivity at 23 degrees C. at a frequency of 40.68 MHz. 
 
     
     
         2 . The high-frequency-dielectric-heating adhesive according to  claim 1 , wherein, when at least one of the three or more adherends is an adherend having the flow start temperature, the flow start temperature TF2 of the at least one of the three or more adherends having the flow start temperature is 90 degrees C. or more. 
     
     
         3 . The high-frequency-dielectric-heating adhesive according to  claim 1 , wherein the flow start temperature TF1 of the high-frequency-dielectric-heating adhesive is in a range from 80 degrees C. to 200 degrees C. 
     
     
         4 . The high-frequency-dielectric-heating adhesive according to  claim 1 , wherein the dielectric property DP2 of all of the three or more adherends is 0.015 or less. 
     
     
         5 . The high-frequency-dielectric-heating adhesive according to  claim 1 , wherein the dielectric property DP1 of the high-frequency-dielectric-heating adhesive is 0.005 or more. 
     
     
         6 . The high-frequency-dielectric-heating adhesive according to  claim 1 , wherein the high-frequency-dielectric-heating adhesive is in a form of an adhesive sheet. 
     
     
         7 . The high-frequency-dielectric-heating adhesive according to  claim 6 , wherein a thickness TS1 of the adhesive sheet and a thickness TS2 of each of the three or more adherends satisfy a relationship of a numerical formula (Numerical Formula 3) below,
   TS1<TS2  (Numerical Formula 3).
   
     
     
         8 . The high-frequency-dielectric-heating adhesive according to  claim 6 , wherein the thickness TS1 of the adhesive sheet is in a range from 5 μm to 2000 μm. 
     
     
         9 . The high-frequency-dielectric-heating adhesive according to  claim 6 , wherein a thickness accuracy of the adhesive sheet is within ±10%. 
     
     
         10 . An assembly comprising: the high-frequency-dielectric-heating adhesive according to  claim 1  and the three or more adherends bonded by the high-frequency-dielectric-heating adhesive. 
     
     
         11 . A producing method of an assembly, the method comprising:
 placing the high-frequency-dielectric-heating adhesive according to  claim 1  between corresponding ones of the three or more adherends; and   applying a high-frequency electric field to the high-frequency-dielectric-heating adhesive to bond the three or more adherends to each other.   
     
     
         12 . The producing method of an assembly according to  claim 11 , wherein the three or more adherends and the high-frequency-dielectric-heating adhesive are placed in between electrodes of a dielectric heating device, and
 the high-frequency electric field is applied while the three or more adherends and the high-frequency-dielectric-heating adhesive are pressed by the electrodes.